With the departure of Henry A. Waxman, the seventh member of his caucus to announce retirement, Democrats will be saying farewell to more than a century and a half of House experience come January. Potential losses by just a couple of veterans in tough midterm races would cost the party six more decades of expertise.

The evolving brain drain has observers of Congress asking several questions: Who in the Democratic Caucus is ready to join the party’s legislative power players? Is that new generation going to be dominated by bipartisan deal-makers or liberal ideologues? Will seniority fade as a predictor of prominence? When will the collective grip of Minority Leader Nancy Pelosi’s team start to slip? How many topflight legislators will be willing to labor at the margins until the Democrats retake the House, given that their next solid shot might not come until the next decade?

The internal dynamics are fluid enough that few clear answers are apparent, and the most adept and ambitious House Democrats are savvy enough to know it’s too early for open boasting about why they should move up the depth chart.

But their legislative top tier is undeniably on the backside of a generational changeover. While Pelosi and House Minority Whip Steny H. Hoyer have provided more than a decade’s worth of stability at the very top of the caucus, no fewer than 10 of the top Democratic seats on committees have changed hands since 2010, the most recent year the party was in control. The number will grow to a dozen with the retirements of Waxman and his California colleague George Miller. (Each chaired a pair of legislative committees in their careers; Waxman is now the ranking member at Energy and Commerce and Miller has that job on Education and the Workforce.) That will leave no more than eight members next year who were chairmen at the end of the last Democratic majority.

Three are in their 80s and two others, Minnesota’s Collin C. Peterson from Agriculture and West Virginia’s Nick J. Rahall II at Transportation, are facing tough races for re-election in generally Republican districts. Rothenberg Political Report/Roll Call rates both the Peterson and Rahall races Leans Democratic.

Beyond that, the retirements announced so far guarantee that no more than one-fifth of next year’s caucus will have experienced 1994, the finale of four straight decades in which the Democrats drove the House’s legislative agenda. At the other end of the seniority spectrum, a quarter of the current membership has known nothing but GOP rule.

Few of those newcomers have had prominent opportunities to display their chops as legislators, but they may take heart in this: None of the Republicans who claimed the keys to the House in 1995 had ever experienced majority power, and yet dozens of them quickly learned to wield gavels with confidence and to practice lawmaking with aplomb.

I asked a dozen CQ Roll Call reporters and editors in recent days to suggest up-and-coming legislative forces, and a relatively limited number of names were mentioned time and again.

At the top is the trio preparing the most obviously for the eventual vacancies at the pinnacle of the hierarchy, each of whom also has significant policymaking credentials. (As a group, they offer a reminder that since last year, and probably for the indefinite future, white men are a plurality but no longer a majority of the Democratic caucus.) Debbie Wasserman Schultz of Florida’s portfolio has become comprehensive while chairing the Democratic National Committee. Chris Van Hollen of Maryland has punched his ticket as head of the caucus campaign organization and is now its pre-eminent face on budget policy. Xavier Becerra of California, where 19 percent of House Democrats live, is a central player for the party on tax, trade, entitlement and immigration matters.

Becerra makes his legislative home on the Ways and Means Committee, but the newsroom’s general consensus is that Richard E. Neal of Massachusetts has the gravitas and collaborative skill to be the party’s most valuable playmaker there for years to come. (At 64, he’s been on the panel for two decades and was the leadership choice for the top seat a few years ago, but the rank and file picked the more liberal Sander M. Levin instead.)

If the caucus turns left over the long term, Texan Lloyd Doggett’s muscular progressivism would boost his prominence on the Ways and Means panel. Moderation becoming the byword would work to the advantage of Wisconsin’s Ron Kind, chairman of the business-friendly New Democrat Coalition. The previous chairman, New York’s Joseph Crowley, is also a force at the committee, but he aspires more to an overarching leadership role.

Two members are mentioned frequently for their combination of breadth of interest, depth of policymaking acumen and insiders’ standing: Robert E. Andrews of New Jersey, who has now set aside his simmering statewide ambitions to pursue interests ranging from education and health care to Pentagon procurement; and Jim McGovern of Massachusetts, the most prominent voice of House liberals on topics including domestic hunger and the war in Afghanistan.

Jared Polis of Colorado, one of McGovern's Rules Committee colleagues, is gaining a reputation as much for his fundraising as for his enterprise on the floor, pushing amendments and procedural tactics that exploit weaknesses in GOP legislative plans.

On Judiciary, the crucible for so many fights over issues important to the base in both parties, Virginia’s Robert C. Scott stands out as a liberal whose commitment to data-based decision-making has earned him the trust and respect of even the most conservative Republicans.

Adam Smith of Washington, the ranking member of Armed Services, is seen as a sober problem-solver and a particularly trustworthy steward for the party on defense matters for years to come. (House Democrats don’t have leadership role term limits.) Adam B. Schiff of California and Henry Cuellar of Texas look to play similar roles as they climb the roster of Appropriations.

The race to fill the top chair at Energy and Commerce looks to be between Frank Pallone Jr. of New Jersey and Anna G. Eshoo of California — unless the 87-year-old dean of the House, John D. Dingell of Michigan, tries to get his old job back . But, whatever that outcome, Colorado’s Diana DeGette and Vermont’s Peter Welch are the more junior members described most frequently as possessing the policy wherewithal, communication skills and deal-cutting desire the Democrats will need to sustain a string of victories over the long term.

But “the next Waxman,” it is clear, is not hiding in plain sight anywhere on the Democratic bench — and expecting to find that person would be naive in any case.

President Barack Obama hailed him as “one of the most accomplished legislators of his or any era.” Given the range and number of bills Waxman pushed to enactment during his 20 terms, almost always with more-than-token GOP backing, that was one State of the Union week proclamation with which it was tough to disagree.